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A new method for thioarsenate preservation in iron-rich waters by solid phase extraction
Maria K Ullrich1, Valentina Misiari1, Britta Planer-Friedrich1
1Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440 Bayreuth, Germany.
Water Research
|July 17, 2016
Summary
A new solid phase extraction (SPE) method effectively preserves iron-rich arsenic samples by separating arsenic species from iron in the presence of sulfide. This technique prevents arsenic sulfide precipitation and speciation artifacts, ensuring accurate analysis.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
Background:
- Traditional methods for preserving iron-rich samples for arsenic speciation analysis are unsuitable in the presence of sulfide.
- Sulfide can lead to arsenic sulfide precipitation and artifact speciation changes, compromising analytical accuracy.
Purpose of the Study:
- To develop and investigate a novel solid phase extraction (SPE) method for preserving arsenic speciation in iron-rich samples containing sulfide.
- To separate anionic arsenic species from cationic iron using SPE.
Main Methods:
- Investigated a solid phase extraction (SPE) method using an anion-exchange resin (AG2-X8).
- Analyzed synthetic solutions containing arsenite, arsenate, monothioarsenate, and trithioarsenate.
- Separated arsenic species from cationic iron (Fe(II)) and analyzed eluent using IC-ICP-MS.
Main Results:
- High retention rates were achieved for arsenate (96.8%), monothioarsenate (98.8%), and trithioarsenate (99.6%) on the anion-exchange resin.
- Cationic iron (Fe(II)) showed minimal retention (0.4%), enabling effective separation.
- Quantitative recovery of retained arsenic species was achieved using salicylate elution.
- The SPE method successfully preserved arsenic speciation in iron-rich natural water samples for up to 6 days.
Conclusions:
- Solid phase extraction (SPE) is a viable and effective method for preserving arsenic speciation in samples containing both iron and sulfide.
- This SPE approach overcomes limitations of traditional preservation methods, enabling accurate arsenic speciation analysis.
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